2012年11月IB生物SL真题下载-Paper2
1. Cells in the alveolus wall produce a surfactant. Its function is to prevent alveoli collapse at the end of expiration. Surfactants are used in the treatment of respiratory system disease in premature babies.
The table shows some of the components of different surfactant preparations
(a) State the surfactant that contains the least amount of phospholipids.
(b) Compare the composition of natural human surfactant with synthetic surfactants.
(c) State one feature of the alveoli, other than the presence of a film of moisture, that adapts them to gas exchange.
(d) Phospholipids found in the surfactants form a surface film on the moist lining of the alveoli. Outline how the hydrophilic and hydrophobic parts of the phospholipids in the surfactants are aligned on the alveolar surface.
The effect of three different surfactants on the growth of three types of bacteria was assessed.Group B streptococci (GBS), Staphylococcus aureus, and Escherichia coli were incubated with three different concentrations of surfactant (1, 10 and 20 mg ml–1).
The bar charts show whether each concentration of surfactant increased or decreased bacterial growth, compared with the growth without surfactant. The difference in growth is shown as colony forming units (CFU) per millilitre.
(e) Identify the effect of increasing the concentration of synthetic surfactant A on the growth of GBS.
(f) Compare the effect of the three surfactants, synthetic surfactants A and B and the modified human surfactant, on the growth of the different bacteria at a concentration of 20 mg ml–1.
(g) Using all the data provided, evaluate the hypothesis that the presence of proteins in surfactants can decrease bacterial growth.
2. (a) Parts of a dichotomous key to organisms A, B, C and D are shown. Design missing parts of the key using features visible in the following diagrams.
(b) All of these organisms belong to the animal kingdom. State two structural differences between animal cells and plant cells.
2012年11月IB生物SL真题余下省略！
你可能还关注